Utility based cross-layer collaboration for speech enhancement in wireless acoustic sensor networks

A wireless acoustic sensor network is considered that is used to estimate a desired speech signal that has been corrupted by noise. The application layer of the WASN derives an optimal filter in a linear MMSE sense. A utility function is then used in conjunction with the MMSE estimate in order to evaluate the most significant signal components from each node in the system. The utility values are used as a cross-layer link between the application layer and the network layer so the nodes transmit the signal components that are deemed most relevant to the estimate while adhering to the power constraints of the system. The simulation results show that a high signal-to-error and signal-to-noise ratio is still achievable while transmitting a subset of signal components

Resource allocation in DMT transmitters with per-tone pulse shaping

International audiencePer-tone pulse shaping has been proposed as an alternative to time domain spectral shaping for DMT transmitters, e.g. VDSL modems. It shapes the spectrum of individual tones such that the stop band energy of each tone can be minimized. This in particular enables transmitter to use more tones without violating the PSD mask constraint for data transmission. In pertone pulse shaping based DMT transmitters a fixed length pulse shaping filter is typically used for every tone. The tones in the middle of the pass band however, contribute less to the overall stop band energy, so that using a high order pulse shaping filter for these tones does not result in a significant reduction of the stop band energy. As a result a significant number of pulse shaping filter taps are wasted on the tones in the middle of the pass band and do not bring any performance gain. Using a variable length pulse shaping filter which is designed such that the PSD mask constraint is not violated can then significantly reduce the total number of pulse shaping filter taps without compromising performance. In this paper, a resource allocation technique is presented for variable length pulse shaping filter design using a dual problem formulation. This optimally solves the problem of pulse shaping filter tap distribution over tones for given PSD mask constraints, with a relatively low complexity

Climate change in Italy indicated by agrometeorological indices over 122 years

To determine the risk of climate change for agriculture it is necessary to define a set of agrometeorological parameters, derived from the classic climate parameters, that are capable of indicating the consequences of climate change for crop production. In this study high-quality daily rainfall, evaporation and mean, minimum and maximum temperature data collected since 1878 at the meteorological station of the Department of Agronomy and Agroecosystem Management of the University of Pisa, Italy (H = 6 in a.s.l.; latitude = 43degrees41'; longitude = 10degrees23'E) were used to calculate extreme temperature and rainfall events, frost risk, flooding risk and drought risk. Time trends for all variables were analysed using linear regression techniques. Results indicate that the changes in extreme events in Pisa have not changed in a way that is likely to negatively affect crop production. The risk of crop damage due to frost has decreased and sowing time in spring can safely be anticipated. The soil moisture surplus (SMS) and theoretical irrigation requirement (TIR) have not changed despite a decreasing rainfall trend. The number of soil moisture surplus days in autumn has decreased indicating a decrease in flooding risk, which can have a positive effect on soil workability. (C) 2002 Elsevier Science B.V. All rights reserved

Dealing with Post-Kogeko

Inter-organizational systems are only used to some extend within the domain of transportation and logistics. Distributed agent technologies show a large potential to build a new generation of inter-organizational systems that overcome the hurdles earlier technologies were not able to take [2, 4]. In this paper we present an ongoing research project in which we try to establish a WebServices based agent platform to be used by a logistics service provider (LSP) in an inter-organizational context – which will connect the LSP’s internal processes, with processes that span organizational boundaries and therefore is likely to result in interesting process improvements; cost savings and improved competitive advantage are expected outcomes. This paper describes the process we followed, and gives a glimp of our preliminary findings. We conclude the paper with a short discussion and our research agenda

An Integrated Weed Management framework: A pan-European perspective

Initiatives to reduce the reliance of agriculture on pesticides, including the European Union (EU) Directive 2009/ 128/EC on the sustainable use of pesticides (SUD), have yet to lead to widespread implementation of Integrated Pest Management (IPM) principles. Developments in weed management have strongly focused on increasing the efficiency of herbicides or substituting herbicides with other single tactics such as mechanical control. To in- crease sustainability of agricultural systems in practice, a paradigm shift in weed management is needed: from a single tactic and single growing season approach towards holistic integrated weed management (IWM) consid- ering more than a single cropping season and focusing on management of weed communities, rather than on control of single species. To support this transition, an IWM framework for implementing a system level approach is presented. The framework consists of five pillars: diverse cropping systems, cultivar choice and establishment, field and soil management, direct control and the cross-cutting pillar monitoring and evaluation. IWM is an integral part of integrated pest management (IPM) and adopting IWM will serve as a driver for the development of sustainable agricultural systems of the futur

Supply Chain Systems Maturing Towards the Internet-of-Things: A Framework

The Internet-of-Things (IoT) concept has been gradually developing, but it is unclear how extensive this concept is adopted within the supply chain domain. We derive an architectural framework to investigate four layers of ICT deployment. This framework enables practitioners and scientist to specify a status quo on different architectural levels and to identify possibilities for further improvement. Four extensive cases are investigated with this framework. One of the important conclusions is that “IoT” like technology and applications are pioneered in research programs, but operational logistic systems in diverse organizations primarily rely on less advanced technology, organizational structures- and work forms. This work can help in identifying gaps where IoT can strengthen future applications